MDKSA-2003:109

Problembeschreibung

A severe vulnerability was discovered in GnuPG by Phong Nguyen
relating to ElGamal sign+encrypt keys. From Werner Koch's email
message:
"Phong Nguyen identified a severe bug in the way GnuPG creates and uses
ElGamal keys for signing. This is a significant security failure
which can lead to a compromise of almost all ElGamal keys used for
signing. Note that this is a real world vulnerability which will
reveal your private key within a few seconds.
Please *take immediate action and revoke your ElGamal signing keys*.
Furthermore you should take whatever measures necessary to limit the
damage done for signed or encrypted documents using that key."
And also:
"Note that the standard keys as generated by GnuPG (DSA and ElGamal
encryption) as well as RSA keys are NOT vulnerable. Note also that
ElGamal signing keys cannot be generated without the use of a special
flag to enable hidden options and even then overriding a warning
message about this key type. See below for details on how to identify
vulnerable keys."
MandrakeSoft urges any users who use the ElGamal sign+encrypt keys to
immediately revoke these keys and discontinue use of them. Updated
packages are provided that remove the ability to create these keys and
to create signatures using these keys (thanks to David Shaw for
writing the patch).